Investigation of the distribution and risk factors associated with Mycobacterium avium subspecies paratuberculosis in cow-calf herds in Canada
Notice bibliographique
Résumé
This thesis summarizes an investigation of Mycobacterium avium subspecies paratuberculosis (Map) as a pathogen within the cow-calf industry in Canada. The specific objectives of this project were to describe the distribution of this pathogen in this industry provincially, as well as at the individual farm level in wildlife species, and in the environment. Secondary objectives of this project were to identify on-farm management risk factors that are associated with this disease and to examine potential options for herd level diagnostic capabilities. Nationally, 0.8% (95%CI = 0.4-1.1%) of the cows in the cow-calf industry were seropositive for Map with 11.7% (95%CI=7.0-16.5%) of the herds sampled having a minimum of one positive test result or 4.5% (95%CI=1.4-7.5%) of the herds having a minimum of two positive test results. The true cow prevalence was estimated as 1.8% (95%CI= 0.4 – 3.1). No Map was detected in any of the non-ruminant wildlife species sampled on cow-calf operations suggesting that these species were not of primary concern when dealing with the management of this disease. In a study not focussed on a cow-calf operation, Map was detected in one cluster of trapped coyote samples in a region with cow-calf production. The prevalence of Map infection in this cluster of coyotes was calculated to be 9.1% (CI: 5.7-12.5). The prevalence of infection in coyotes including all sites, ignoring the effect of clustering, was calculated to be 3.7% (CI: 2.3-5.1). The use of a commercial colostrum replacement on farm (Odds Ratio =3.96; 95% CI = 1.10–14.23, p=0.035) and the presence of wild deer interacting with the cattle (Odds Ratio = 14.32; 95% CI = 1.13–181.90, p=0.040) were positively associated with being a herd infected with paratuberculosis. The use of rotational grazing practices was protective (Odds Ratio = 0.20; 95% CI = 0.04–0.93, p=0.039). It was possible to detect environmental contamination with Map on cow-calf farms using bacterial culture and PCR for confirmation. No water samples were positive to Map; however, 6.2% of the non-water environmental samples were positive. The use of an environmental sampling protocol had a herd sensitivity of 29.6%. This finding led to a simulation modelling study to evaluate how various testing methods would compare in the broader population of cow-calf herds. The final mean risk of selecting a herd infected with Map that was not identified as positive via the herd screen test strategy was 12.9%, 9.8%, 9.6%, and 6.1% for no herd screen test, environmental sampling, ELISA serology, and pooled fecal culture strategies, respectively.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,002 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,002 | 0,002 |
| Études des sciences et des technologies | 0,002 | 0,001 |
| Communication savante | 0,001 | 0,000 |
| Science ouverte | 0,001 | 0,001 |
| Intégrité de la recherche | 0,001 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».